Research of treatment of wastewater from milk collection stations in sand filter
2008
Askinis, S., Lithuanian Univ. of Agriculture, Kaunas (Lithuania). Water Management Inst.
Highly polluted wastewater accumulates in milk collection stations. Its biochemical oxygen demand (BOD5) ranges from 369 to 1388 mg O2 lE-1. The average contamination was 600 mg O2 lE-1. There was a comparatively small amount of biogenic materials in it: total nitrogen – 27.3, total phosphorus – 5.0 mg lE-1. When variations of wastewater amounts are high, sand filters of vertical filtration are successfully used for the treatment of household wastewater. Model investigations were carried out to establish the possibilities of using these filters in treating wastewater in milk collection stations. The efficiency of wastewater treatment with these filters was 99.3% by BOD5, 99.1% – by suspended solids, 91.2% – by total nitrogen and 98.8% – by total phosphorus. According to the research results dependency equations were made; they were used to calculate the amount of main contaminants in milk collection stations that infiltrated through a layer of silt of diff rent thickness. The calculations showed that wastewater treatment to permissible limits is ensured by filtration through 0.6 m thick layer of sand. The average treatment level by BOD5 in such a filter of vertical filtration would be 20 mg O2 lE-1 and the treatment efficiency – 95.9%. Treatment efficiency of total nitrogen would be 88.1%, total phosphorus – 96.9, suspended solids – 95.5%. Preliminary research in the model showed that sand filters of vertical filtration can be used to treat wastewater from milk collection stations.
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